How frequently should an electrical thermography audit be conducted?

NFPA 70B recommends annual thermographic surveys for electrical systems in commercial and industrial facilities. Many Singapore insurance underwriters and facility management standards align with this. Facilities with high fire risk (data centres, hospitals, warehouses with combustible goods), continuous operation requirements, or a history of electrical faults should conduct audits every six months. After any significant modification to the electrical distribution system, a targeted thermographic inspection of the modified areas is recommended regardless of the annual audit schedule.

Does a thermography audit satisfy Singapore insurer requirements?

Many Singapore property and business interruption insurers accept thermography audit reports as evidence of proactive electrical maintenance, which can influence premium calculations or be a condition of cover for high-value electrical installations. Insurers typically require that the report reference calibrated instruments, a recognised classification standard, and that the inspector holds recognised qualifications. A report that identifies findings and shows a documented remediation plan is more valuable to underwriters than one that simply reports a clean bill of health.

Can we conduct a thermography audit if some panels are inaccessible?

Panels that cannot be safely accessed during an energised inspection should be noted in the report as "not inspected — access not possible" with the reason stated. For permanently inaccessible panels (sealed panels, panels in energised HV substations beyond the scope of LV inspection), the audit plan should include a note of the limitation and a recommendation for the appropriate inspection method (e.g., specialist HV thermography, scheduled outage inspection). Incomplete coverage is a finding in itself and should be reported honestly.

What qualifications does the thermographer need?

The thermographer should ideally hold a recognised infrared thermography certification — commonly the ISO 18436-7 Level I or Level II certification, or an equivalent certification from a recognised training body. For Singapore-specific legal requirements, the opening of live LV panel doors must involve a licensed electrical worker as defined by the Electricity (Electrical Workers) Regulations. The thermographer and the licensed electrical worker may be the same person if both qualifications are held, or the thermographer may work alongside a licensed electrician who controls panel access.

Electrical Thermography Audit Planning Guide | Unitest Instruments Singapore

An electrical thermography audit is a systematic infrared inspection of a facility's entire electrical distribution system — from the main incoming switchboard through sub-distribution boards, motor control centres, and distribution panels — conducted to identify overheating components and connections before they cause electrical faults, fires, or unplanned downtime. A well-planned and properly executed thermography audit, repeated annually or semi-annually, is widely accepted by Singapore insurers as evidence of due-diligence fire prevention and is increasingly referenced in the Singapore Civil Defence Force (SCDF) Fire Code 2023 as a recommended practice for buildings with significant electrical infrastructure.

This guide takes you through the complete audit lifecycle: defining scope, satisfying Singapore regulatory safety requirements, executing the inspection to a professional standard, classifying findings, and producing a report that is useful to maintenance planners, insurance underwriters, and compliance auditors.

Defining the Audit Scope

The first step in planning a thermography audit is defining which equipment will be included. A comprehensive electrical thermography audit for a Singapore commercial building or industrial facility typically covers:

Main incoming switchboard (MSB) and HV/LV transformer terminals
Main distribution boards (MDB)
Sub-distribution boards (SDB) and final sub-circuit panels
Motor control centres (MCC) and variable speed drive panels
Power factor correction (PFC) capacitor banks
UPS systems and static transfer switches
Generator AMF/ATS panels and generator terminal boxes
External cable terminations (where accessible)
Busduct (busbar trunking) joint boxes

For facilities with high-voltage switchgear (11 kV or above), HV switchgear inspection requires specialist thermographers with HV electrical worker licensing and appropriate HV-rated PPE — a significantly more complex and hazardous undertaking than LV panel inspection.

Define the scope in a written Inspection Plan before starting work. The Inspection Plan should list every panel to be inspected, the order of inspection, the access requirements for each panel, and the safety controls applicable to each location.

Safety Planning and Permit Requirements

Electrical thermography is energised electrical work. In Singapore, it falls within the scope of the Electricity Act and the Workplace Safety and Health (Electrical Installations) Regulations. Key safety requirements:

Licensed electrical workers: Opening live low-voltage panel doors requires the involvement of a licensed electrical worker (Electrician or above under the EMA licensing framework). For HV equipment, a licensed HV electrical worker is required.
Arc flash PPE: Where arc flash risk exists (which applies to most LV switchboards above a certain prospective short circuit current), arc-rated PPE must be worn. This includes arc flash face shield, arc-rated gloves, arc-rated clothing, and insulating footwear. The incident energy should be assessed per IEEE 1584 or a Singapore-equivalent arc flash study.
Permit to Work: Most facilities require a Permit to Work (PTW) for any energised electrical work. Obtain PTW approval before commencing the inspection and ensure all relevant parties are informed.
Emergency procedures: Confirm emergency isolation procedures and first-aid provisions are in place before opening any energised panel.

Thermal Camera Setup and Calibration

Camera setup directly affects the accuracy and comparability of temperature measurements. Before beginning the inspection:

Record ambient temperature: Measure and record the ambient air temperature in each electrical room. This is required for temperature rise calculations and for applying correction factors if comparing readings to historical data taken at different ambient temperatures.
Set emissivity: Set the camera's emissivity to match the material being measured. Bare copper: ε ≈ 0.02–0.05 (very low — hard to measure accurately). Oxidised copper: ε ≈ 0.4–0.7. Painted or insulated components: ε ≈ 0.85–0.95. For accurate absolute temperature measurement of copper conductors, applying a small patch of black electrical tape (ε ≈ 0.95) and measuring the tape temperature is a practical workaround.
Confirm focus and resolution: The thermal image must be in sharp focus and the hotspot must occupy a minimum area on the detector (typically 3×3 pixels or more) for the spot temperature reading to be reliable.
Record instrument details: Camera make, model, serial number, and current calibration certificate reference must be recorded in the inspection log for the report.

Thermal cameras used for quantitative electrical inspections should be calibrated at defined intervals, with calibration traceable to national standards. Unitest Instruments provides SAC-SINGLAS accredited calibration for thermal cameras as part of its comprehensive calibration service offering.

Inspection Technique: Systematic Panel Coverage

A systematic inspection technique ensures that no components are missed and that findings are reproducible. For each panel:

Photograph the panel front (door closed) with panel label visible — for the report
Open the panel door (with appropriate PPE, involving licensed electrical worker)
Conduct an initial full-panel thermal scan from a safe distance before approaching closer
If no anomalies are visible at initial scan distance, approach to the working distance appropriate for the camera's detector resolution and lens focal length
Systematically scan the panel in sections: incoming terminals and busbars, then each outgoing circuit breaker, then neutral and earth bars
For any identified hotspot: capture both thermal and visible-light images (use the camera's fusion function if available), measure Tmax, identify and measure Tref on an adjacent identical component, record load current on the affected phase
Photograph each hotspot with panel label and circuit identifier visible in the visible-light image
Close panel door
Record inspection completion in the log

Hotspot Classification and Severity Rating

Each hotspot identified must be classified by severity to guide maintenance prioritisation. The most widely used classification system uses temperature rise (ΔT) above an identical reference component:

ΔT Above Reference	Severity	Action
1–10 °C	1 — Monitor	Record and re-inspect at next scheduled survey
10–20 °C	2 — Investigate	Inspect and repair at next planned outage
20–40 °C	3 — Urgent	Repair within defined short window; increase monitoring
>40 °C	4 — Critical	Immediate repair; consider de-energising if risk allows

Note that absolute temperature also matters — a component at 65°C in a 20°C ambient (ΔT = 45°C) is critical by ΔT classification and also approaching the standard 70°C maximum for most switchboard components. Always report both ΔT and absolute temperature in the finding record.

For findings where no comparable reference component exists (e.g., the main incoming terminals on a single-feed MSB), compare against the rated temperature for the component (from OEM data or IEC standards) rather than a reference component.

Report Structure and Content

The thermography audit report is the deliverable that maintenance planners, insurance underwriters, and compliance auditors will rely on. A professional report should contain:

Executive summary: Total number of panels inspected, total findings by severity class, key risk items, and recommended immediate actions
Scope and methodology: Equipment surveyed, date and time, ambient conditions, camera details and calibration certificate reference, inspection standard reference (NFPA 70B, EN 13187, or equivalent)
Finding sheets (one per finding): Panel ID, circuit ID, component description, thermal image, visible-light image, Tmax, Tref, ΔT, ambient temperature, load current, severity classification, and recommended action with priority
Summary findings table: All findings in a single table, sortable by severity, panel, and action status
Inspection completion record: All panels inspected (including those with no findings) with date and inspector sign-off
Inspector qualifications: Name, thermography certification level, electrical licence details if applicable

Post-Audit Actions and Tracking

A thermography audit report has no value unless findings are acted upon. Each finding should generate a work order in the CMMS with an assigned priority and completion deadline. Critical findings (Severity 4) should trigger immediate action regardless of whether a planned outage is scheduled. Urgent findings (Severity 3) should be completed within the next planned maintenance window.

After repairs are completed, a follow-up thermographic inspection of the repaired components confirms success. This before/after evidence is valuable for insurance purposes and demonstrates that the maintenance programme is closed-loop rather than merely identifying problems.

For the next scheduled audit, the previous report's findings summary provides the baseline for comparison — panels that had multiple findings in the previous cycle may warrant more frequent monitoring or a closer look at load distribution and connection maintenance practices.

To discuss thermal cameras suited to electrical panel auditing or to enquire about calibration services for your existing thermal camera, contact Unitest Instruments. Related reading: thermal imaging for electrical panel inspection and thermal imaging in predictive maintenance.

Electrical Thermography Audit: Planning, Execution and Reporting